Magnetic bearing cell

Abstract

There is disclosed a magnetic bearing cell of rotationally symmetrical construction, which includes a rotor having two rotating permanent ring magnets and a stator having a damping disk that projects into a first gap between the permanent ring magnets of the rotor. In order to improve the radial stability of the cell an additional permanent ring magnet is secured to the shaft and is spaced apart from one of the rotating permanent ring magnets to define a second gap therebetween. A ring disk that is secured to the stator projects into the second gap, the ring disk carrying an axially magnetized stator permanent ring magnet in the vicinity of the rotating permanent ring magnets of the rotor.

We claim: 
     
       1. A magnetic bearing cell that is rotationally symmetric about a central axis, comprising: a rotor for rotation about said central axis, said rotor having a shaft and two axially magnetized permanent ring magnets that are secured to the shaft for rotation therewith and axially separated from one another to define a first gap therebetween;   a stator having two ring coils, pole elements, and a first ring disk, said first ring disk being fabricated of a non-magnetizable material having high electrical conductivity, said first ring disk projecting into said first gap of said rotor;   structural elements of said rotor and said stator being disposed relative to one another to generate a toroidal magnetic flux that surrounds said central axis;   a further permanent ring magnet disposed between said pole elements of said stator and secured to said shaft, and separated from said two axially magnetized permanent ring magnets by a second gap;   a second ring disk secured to said stator that projects into said second gap said second ring disk carrying an axially magnetized stator permanent ring magnet that is disposed in a vicinity of said two axially magnetized permanent ring magnets.   
     
     
       2. The magnetic bearing cell according to claim 1, wherein said second ring disk comprises a nonmagnetizable carrier material. 
     
     
       3. The magnetic bearing cell according to claim 2, wherein said carrier material has a high level of electrical conductivity. 
     
     
       4. The magnetic bearing cell according to claim 3, wherein said carrier material is copper. 
     
     
       5. The magnetic bearing cell according to claim 1, wherein said first ring disk and said second ring disk each have peripheral cylindrical portions that lie against an interior surface of a said pole element. 
     
     
       6. The magnetic bearing cell according to claim 1, wherein said two axially magnetized permanent ring magnets, said further permanent ring magnet, and said stator permanent ring magnet are all disposed substantially in a common cylindrical surface of revolution that is coaxial with said central axis.